from wayne:
"The diurnal options should be pre and post noon, as you have it, but also—and likely more usefully—daylight and night (which is best approximated as 6am-6pm cutoffs for the local solar time). Also it may be possible to add a user option of the periods: e.g. the user inputs 2 numbers such as 05:30 and 18:30 which gives two periods—an 11 hour night and 13 hour day. This may be better for someone who has summer data and so on."
from wayne: "The diurnal options should be pre and post noon, as you have it, but also—and likely more usefully—daylight and night (which is best approximated as 6am-6pm cutoffs for the local solar time). Also it may be possible to add a user option of the periods: e.g. the user inputs 2 numbers such as 05:30 and 18:30 which gives two periods—an 11 hour night and 13 hour day. This may be better for someone who has summer data and so on."